Discharging method of bus capacitor, controller, DC-DC converter and inverter

Patent metadata

Field	Value
Publication number	US-10320294-B2
Application number	US-201715474045-A
Country	US
Kind code	B2
Filing date	Mar 30, 2017
Priority date	Jun 30, 2016
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A discharging method of a bus capacitor, a controller, a DC-DC converter and an inverter are provided. After a DC-DC converter or an inverter is powered off, in a case that a detected voltage across a bus capacitor of the DC-DC converter or the inverter is determined to meet a preset condition, a switch of the DC-DC converter or the inverter is controlled to be turned on or turned off to cause the bus capacitor, the switch, and a reactor of the DC-DC converter or the inverter to form a current loop, until the voltage does not meet the preset condition. Based on the method, discharging function is achieved for the bus capacitor after the DC-DC converter or the inverter is powered off, without the need for an additional discharging circuit, which solves problems caused by the additional discharging circuit required in the conventional technology.

First claim

The invention claimed is:

1. A discharging method of a bus capacitor, applied to a controller of a DC-DC converter, wherein the DC-DC converter comprises the bus capacitor, a switch and a reactor, and the discharging method of the bus capacitor comprises:
detecting a voltage across the bus capacitor;
determining whether the voltage across the bus capacitor meets a preset condition, after the DC-DC converter is powered off; and
controlling, in a case that the voltage across the bus capacitor meets the preset condition, the switch to be turned on or turned off to cause the bus capacitor, the switch and the reactor to form a current loop for consuming residual power of the bus capacitor, until the voltage across the bus capacitor does not meet the preset condition;
wherein the DC-DC converter is a bi-directional DC-DC converter, the bus capacitor comprises a first bus capacitor and a second bus capacitor, the switch comprises a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series, and two series connection points are respectively connected to two terminals of the reactor; and
wherein the controlling, in a case that the voltage across the bus capacitor meets the preset condition, the switch to be turned on or turned off to cause the bus capacitor, the switch and the reactor to form a current loop for consuming residual power of the bus capacitor, until the voltage across the bus capacitor does not meet the preset condition comprises:
controlling, in a case that a voltage across the first bus capacitor meets the preset condition, the fourth switch to be turned on, and controlling the first switch to be turned on in response to a first preset periodic pulse, until the voltage across the first bus capacitor does not meet the preset condition, wherein in each period of the first preset periodic pulse, a current in the reactor decays to zero in a turn-off time of the first switch; and
controlling, in a case that a voltage across the second bus capacitor meets the preset condition, the second switch to be turned on, and controlling the third switch to be turned on in response to the first preset periodic pulse, until the voltage across the second bus capacitor does not meet the preset condition, wherein in each period of the first preset periodic pulse, a current in the reactor decays to zero in a turn-off time of the third switch.

2. The discharging method of the bus capacitor according to claim 1 , wherein the determining whether the voltage across the bus capacitor meets a preset condition comprises: determining whether the voltage across the bus capacitor is higher than or equal to a discharging threshold.

3. A controller applied to a DC-DC converter, wherein the DC-DC converter comprises a bus capacitor, a switch and a reactor, and the controller comprises:
a detecting unit, configured to detect a voltage across the bus capacitor;
a determining unit, configured to determine whether the voltage across the bus capacitor meets a preset condition, after the DC-DC converter is powered off; and
a controlling unit, configured to control, in a case that the voltage across the bus capacitor meets the preset condition, the switch to be turned on or turned off to cause the bus capacitor, the switch and the reactor to form a current loop for consuming residual power of the bus capacitor, until the voltage across the bus capacitor does not meet the preset condition;
wherein the DC-DC converter is a bi-directional DC-DC converter, the bus capacitor comprises a first bus capacitor and a second bus capacitor, the switch comprises a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series, and two series connection points are respectively connected to two terminals of the reactor; and
wherein controlling, in a case that the voltage across the bus capacitor meets the preset condition, the switch to be turned on or turned off to cause the bus capacitor, the switch and the reactor to form the current loop for consuming residual power of the bus capacitor, until the voltage across the bus capacitor does not meet the preset condition comprises one of:
1) controlling, in a case that a voltage across the first bus capacitor meets the preset condition, the fourth switch to be turned on, and controlling the first switch to be turned on in response to a first preset periodic pulse, until the voltage across the first bus capacitor does not meet the preset condition, wherein in each period of the first preset periodic pulse, a current in the reactor decays to zero in a turn-off time of the first switch; and
controlling, in a case that a voltage across the second bus capacitor meets the preset condition, the second switch to be turned on, and controlling the third switch to be turned on in response to the first preset periodic pulse, until the voltage across the second bus capacitor does not meet the preset condition, wherein in each period of the first preset periodic pulse, a current in the reactor decays to zero in a turn-off time of the third switch; and
2) controlling, in a case that the voltage across the first bus capacitor and/or the voltage across the second bus capacitor meet the preset condition, a first switch group and a second switch group to be alternately turned on or turned off, until neither the voltage across the first bus capacitor nor the voltage across the second bus capacitor meets the preset condition, wherein the first switch group is controlled to be turned on or turned off in response to a second preset periodic pulse, the second switch group is controlled to be turned on or turned off in response to a third preset periodic pulse;
wherein duty ratios of the second preset periodic pulse and the third preset periodic pulse are the same, and the second preset periodic pulse and the third preset periodic pulse are different in phase so that the first switch group and the second switch group are not simultaneously turned on;
wherein the first switch group comprises the first switch and the fourth switch that are simultaneously turned on or turned off, and the second switch group comprises the second switch and the third switch that are simultaneously turned on or turned off; and
wherein each time both the first switch group and the second switch group are turned off, a current in the reactor decays to zero.

4. The controller according to claim 3 , wherein when the determining unit is configured to determine whether the voltage across the bus capacitor meets the preset condition, the determining unit is specifically configured to determine whether the voltage across the bus capacitor is higher than or equal to a discharging threshold.

5. The DC-DC converter, comprising: a first circuit breaker, a second circuit breaker, a first contactor, a second contactor, a first bus capacitor, a second bus capacitor, a first switch, a second switch, a third switch, a fourth switch, the reactor and the controller according to claim 3 , wherein
the first switch, the second switch, the third switch and the fourth switch are each provided with an anti-parallel diode;
an emitter of the first switch is connected to a collector of the second switch, and a connection point is connected to a terminal of the reactor;
an emitter of the third switch is connected to a collector of the fourth switch, and a connection point is connected to the other terminal of the reactor;
a collector of the first switch is connected to a terminal of the first bus capacitor and is connected to a positive electrode of a first terminal of the first circuit breaker via the first contactor;
an emitter of the second switch is connected to the other terminal of the first bus capacitor and a negative electrode of the first terminal of the first circuit brea

Assignees

• Sungrow Power Supply Co Ltd

Inventors

• Jiang Tao
• Chen Peng
• Wang Xiaofei
• Li Fei

Classifications

• H02M3/158 Primary

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02M3/1582 Primary

  Buck-boost converters (H02M3/1584 takes precedence) · CPC title

• H02M7/537

  using semiconductor devices only, e.g. single switched pulse inverters · CPC title

• H02M2001/322

  Electricity · mapped topic